Greater Sydney in autumn 2021: Wetter and cooler than average

Above average rainfall and cooler than average temperatures

Dry end to autumn

  • Despite a dry April and close to average May, March rainfall was at least three times the average at most sites, resulting in above average autumn rainfall.
  • Generally rainfall was at least 25% more than the 1961–1990 average
  • Some sites recorded more than twice their long-term average rainfall for autumn.
  • Most areas experienced very heavy rain over the period from 17 to 26 March.
  • A coastal trough combined with a cold front, and brought heavy rain at the start of May.
  • Some sites had their highest autumn daily rainfall on record.
  • Some sites had their highest total autumn rainfall on record or their highest total autumn rainfall for at least 20 years.

Cooler than average

  • Many sites recorded cooler than average temperatures during autumn, particuarly for minimum temperatures.
  • Daytime temperatures were cooler than average for March, and during April were the coolest since April 2017.
  • Mean minimum temperatures were close to average during March and cooler than average during April.
  • Katoomba recorded its lowest autumn temperature on record, which was the coolest night since 26 July 1986.

Sydney (Observatory Hill)

  • Total rainfall for Sydney (Observatory Hill) was 499.4 mm, which is 25% more the long-term average of 375.5 mm at the former Sydney (Observatory Hill) site.
  • The mean daily maximum temperature for Sydney (Observatory Hill) was 23.6 °C, which is 1.3 °C more than the long-term average at the former Sydney (Observatory Hill) site.
  • The warmest day was 31.2 °C on 8 March, and the coolest day was on 29 May when the temperature reached 16.0 °C
  • The mean daily minimum temperature for Sydney (Observatory Hill) was 14.6 °C, which is 0.1 °C less than the long-term average at the former Sydney (Observatory Hill) site.
  • The coldest morning was 7.8 °C on 16 May, and the warmest morning was on 12 March when the minimum temperature was 21.4 °C

Extreme rainfall and flooding in March

  • Extreme multi-day rainfall and significant flooding affected most of New South Wales over the period from 17 to 26 March.
  • The Hawkesbury–Nepean catchment in Sydney experienced its most significant flooding in more than 30 years.
  • More information on the rainfall and flooding is available in Special Climate Statement 74.

Further information

Media
(03) 9669 4057

Extremes in autumn 2021
Hottest day 35.6 °C at Bankstown Airport AWS on 1 Mar
35.6 °C at Richmond RAAF on 1 Mar
Warmest days on average 24.0 °C at Penrith Lakes AWS
Coolest days on average 16.7 °C at Mount Boyce AWS
Coldest day 6.9 °C at Mount Boyce AWS on 15 May
Coldest night -5.1 °C at Katoomba (Farnells Rd) on 30 May
Coolest nights on average 8.0 °C at Mount Boyce AWS
Warmest nights on average 16.1 °C at Sydney Harbour (Wedding Cake West)
Warmest night 22.2 °C at Sydney Harbour (Wedding Cake West) on 10 Mar
22.2 °C at Norah Head AWS on 12 Mar
Warmest on average overall 19.2 °C at Norah Head AWS
Coolest on average overall 12.4 °C at Mount Boyce AWS
Wettest overall 768.7 mm at Katoomba (Farnells Rd)
Wettest day 205.3 mm at Mt Irvine (Booralee) on 22 Mar
Strongest wind gust 104 km/h at Wattamolla AWS on 6 May

Record highest autumn daily rainfall
New record
(mm)
Old
record
Years of
record
Oakdale (Cooyong Park) 166.0 on 21 Mar 162.1 on 16 Apr 1969 45
Collaroy (Long Reef Golf Club) 152.2 on 21 Mar 119.6 on 13 Apr 1971 39
Mt Irvine (Booralee) 205.3 on 22 Mar 117.0 on 1 Apr 2009 35
Mangrove Mountain AWS 130.0 on 21 Mar 124.0 on 30 Mar 2002 27
Mount Boyce AWS 110.8 on 21 Mar 105.2 on 21 Apr 2015 27
Badgerys Creek AWS 109.2 on 21 Mar 83.6 on 21 Apr 2015 26
Penrith Lakes AWS 105.4 on 21 Mar 85.6 on 21 Apr 2015 26
Gorokan (Goobarabah St) 111.0 on 21 Mar =111.0 on 24 Apr 2008 25
Lower Mangrove (Popran Rd) 149.0 on 21 Mar 136.8 on 21 Apr 2015 23
Blackheath (Wombat Street) 140.0 on 21 Mar 113.0 on 21 Apr 2015 22
Concord (Brays Rd) 127.2 on 21 Mar 124.0 on 21 Apr 2015 22
Abbotsbury (Fairfield (City Farm)) 110.0 on 21 Mar 75.0 on 21 Apr 2015 21
Menangle Bridge (Nepean River) 86.0 on 21 Mar 84.0 on 1 Mar 2007 21
Wyong (Mount Elliot) 133.0 on 21 Mar 131.0 on 22 Apr 2015 21
Mount Annan (Australian Botanic Garden) 92.0 on 21 Mar 86.0 on 19 Apr 2012 20



Record highest autumn total rainfall
New record
(mm)
Old
record
Years of
record
Average for
autumn
Mount Boyce AWS 655.0 479.4 in 2017 27 250.0
Mangrove Mountain AWS 716.4 582.0 in 2017 26 316.8
Penrith Lakes AWS 496.0 352.8 in 2015 26 174.6
Badgerys Creek AWS 445.8 361.8 in 2015 25 182.3
Blackheath (Wombat Street) 750.0 522.0 in 2009 21 269.1
Abbotsbury (Fairfield (City Farm)) 434.0 362.0 in 2015 20 194.0

Highest autumn total rainfall for at least 20 years
Observed
(mm)
Most recent
higher
Average for
autumn
Mount Wilson (Clarine) 653.5 756.1 in 1978* 349.4
Camden (Brownlow Hill) 431.0 476.6 in 1988* 200.4
Richmond - UWS Hawkesbury 461.1 566.6 in 1989* 214.8
Springwood (Valley Heights) 643.2 650.1 in 1989* 288.4
Katoomba (Farnells Rd) 768.7 812.0 in 1989* 391.9
Kurrajong Heights (Bells Line of Road) 664.1 696.0 in 1989* 340.7
Bringelly (Maryland) 409.0 587.4 in 1988* 214.0
Camden Airport AWS 423.2 517.9 in 1988* 213.5
Faulconbridge (St Georges Crescent) 645.0 646.4 in 1990* 293.5
Wedderburn (Booalbyn) 444.0 610.0 in 1978* 218.2
Campbelltown (Kentlyn (Georges River Roa 413.0 525.9 in 1988* 219.8

* note: there are gaps in the historical record at this site, so it is possible a higher value has gone unreported




Record lowest autumn temperature
New record
(°C)
Old
record
Years of
record
Average for
autumn
Katoomba (Farnells Rd) -5.1 on 30 May -2.8 on 31 May 1977 58 8.8



Summary statistics for autumn 2021
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
autumn
2021
Diff
from
average
Highest for
autumn
2021
Mean for
autumn
2021
Diff
from
average
Lowest for
autumn
2021
Total for
autumn
2021
Average
for
autumn
Rank of
autumn
2021
Fraction of
autumn
average
Badgerys Creek AWS 23.4 -0.5 34.9 1 Mar 10.9 -0.6 2.2 23 Apr 445.8 182.3 highest 245%
Bankstown Airport AWS 23.6 0.0 35.6 1 Mar 12.4 -0.4 4.6 16 May 398.6 249.4 high 160%
Camden Airport AWS 23.0 -0.8 34.2 1 Mar 10.4 -0.6 0.7 20 May 423.2 213.5 v high 198%
Campbelltown (Mount Annan)     34.8 1 Mar 10.8 -0.5 2.4 20 May 359.8 188.9 v high 190%
Canterbury Racecourse AWS 22.9 -0.5 31.1 8 Mar 12.0 -0.9 4.1 20 May 520.8 271.4 high 192%
Cooranbong (Lake Macquarie AWS) 23.4 -0.8 32.4 9 Mar 11.3 -0.7 2.8 20 May 504.0 288.5 v high 175%
Gosford AWS 22.8   30.7 1 Mar 13.1   5.5 19 May 590.4
Holsworthy Aerodrome AWS 22.9   34.5 1 Mar 11.9   3.0 20 May 400.6
Holsworthy Defence AWS 22.3   35.2 1 Mar 11.6   4.2 20 May 404.8
Horsley Park Equestrian Centre AWS 23.0 -0.8 35.0 1 Mar 12.0 -0.7 3.4 17 May 371.6 204.3 v high 182%
Katoomba (Farnells Rd) 17.1 +0.3 27.8 1 Mar     -5.1 30 May 768.7 391.9 v high 196%
Mangrove Mountain AWS 21.9 0.0 32.6 1 Mar 11.2 -0.9 2.4 16 May 716.4 316.8 highest 226%
Mount Boyce AWS 16.7 -0.4 26.7 1 Mar 8.0 -0.7 -0.8 16 May 655.0 250.0 highest 262%
Norah Head AWS 23.0 +0.1 31.3 9 Mar 15.5 -0.5 8.4 17 May 529.2 376.3 high 141%
Parramatta North (Masons Drive) 23.2 -0.4 34.5 1 Mar 12.0 -0.9 4.5 15 May 440.0 270.5 high 163%
Penrith Lakes AWS 24.0 -0.5 35.5 1 Mar 12.2 -0.9 3.5 17 May 496.0 174.6 highest 284%
Richmond RAAF 23.6 -0.5 35.6 1 Mar 11.4 -0.3 1.6 28 May 425.2 187.0 v high 227%
Springwood (Valley Heights) 21.4 -0.9 33.4 1 Mar 12.1 -0.4 5.6 16 May 643.2 288.4 v high 223%
Sydney (Observatory Hill) 23.6   31.2 8 Mar 14.6   7.8 16 May 499.4
Sydney Airport AMO 23.1 +0.2 33.1 8 Mar 14.8 +0.5 7.7 16 May 457.6 320.9 high 143%
Sydney Harbour (Wedding Cake West) 21.9 -0.2 30.1 8 Mar 16.1 -0.4 9.8 16 May
Sydney Olympic Park AWS (Archery Centre) 23.6   33.3 1 Mar 13.0   5.4 18 May 436.2 296.3 high 147%
Terrey Hills AWS 21.5 -0.7 30.1 13 Mar 13.3 -0.6 5.8 17 May 550.2 322.8 v high 170%

Notes

The Seasonal climate summary, generally published on the first working day of each month, lists the main features of the weather in Greater Sydney using the most timely and accurate information available on the date of publication; it will generally not be updated. More extensive discussion of significant weather events, along with later information and data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review.

This summary includes data from observing sites in or near the Greater Sydney “Greater Capital City Statistical Area” (GCCSA). The Australian Bureau of Statistics designed the GCCSAs to “include the population within the urban area of the city, as well as people who regularly socialise, shop or work within the city, and live in small towns and rural areas surrounding the city. It is important to note that GCCSAs do not define the built up edge of the city. They provide a stable definition for these cities and are designed for the output of a range of social and economic survey data.

This statement has been prepared based on information available at 9 am on Tuesday 1 June 2021. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

In some situations, some or all of the rainfall is in the form of hail or snow. In these cases the totals given are for the water equivalent: the depth of liquid water that results from melting any frozen precipitation. There can be significant 'undercatch' of snow in strong winds, meaning the true precipitation can be higher than that reported.

Averages for individual sites are long-term means based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Where temperature area averages are mentioned, they are derived from the ACORN-SAT dataset.

Further information

Media
(03) 9669 4057

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